Universal Design in Plain Terms
Why this matters
Most of the houses your crews will ever touch belong to people who do not have a disability today and will have one, or live with someone who does, before they sell. When that day comes, the expensive part is undoing choices made on ordinary jobs: the shower valve set where only a standing adult can reach it, the closed-up wall with no blocking in it, the switch behind the door swing. Universal design is the habit of making those ordinary choices so the default works for more bodies. It is not a product line or a special job. It is a way of deciding, and it costs almost nothing when it is applied while the wall is already open.
What universal design is, and what it is not
Universal design is designing products and spaces to be usable by as many people as possible, of any age, size or ability, without adaptation or a special version. The working definition and the seven principles below come from the Center for Universal Design at North Carolina State University, published in 1997 by a group led by the architect Ron Mace.
It is easiest to understand by what it is not:
- It is not accessible design. Accessible design targets a known disability and a standard: a roll-in shower for a wheelchair user, built to measured clearances. Universal design targets the default: the shower that a child, a tall adult, a person with a cast and a person who sits to wash can all use.
- It is not a code. No building code requires the seven principles. The 2010 ADA Standards are a compliance document for public buildings; universal design borrows their dimensions as a reference but is not measured against them. See related: What the ADA Does and Does Not Cover in a Private Home.
- It is not a look. The point is that nothing reads as medical. A grab bar that doubles as a towel bar, a zero-step entry that just looks like a good entry, a lever faucet that is simply the faucet.
The seven principles, as decisions a trade makes
Each principle below is stated in its plain form, followed by the choices it drives on everyday work in several trades.
1. Equitable use: one way in, for everyone. The same means of use for every user, identical where possible, never a segregated alternative. On the job: a single entry that has no step rather than a ramp around the back; a front-loading washer on a pedestal everyone can load; a thermostat in the hallway everyone passes, not in the back bedroom.
2. Flexibility in use: more than one way to do it. Right or left hand, seated or standing, fast or slow. On the job: a handheld shower on a slide bar instead of a fixed head, so the same fixture serves a standing adult, a seated bather and a parent washing a child; a door that can be opened from either side of its latch with either hand; a garage door opener with both a wall button and a keypad.
3. Simple and intuitive: it works the way people expect. No instructions needed, consistent with what the user already knows. On the job: a thermostat with up and down arrows and a readable display rather than a menu; a single control on the shower that sets temperature by turning one way and flow by lifting; shutoff valves that are all quarter-turn so the open-closed position is obvious from the handle.
4. Perceptible information: it tells you, more than one way. Information reaches the user whatever their vision or hearing, through sight, sound and touch together, with enough contrast. On the job: breaker directories written legibly and in plain room names; a contrasting stripe at a stair nosing; a smoke alarm that is heard throughout the house and, where someone cannot hear it, seen. See related: Contrast and Cues for Low Vision; Alerts for a Customer With Hearing Loss.
5. Tolerance for error: a mistake should not hurt. Minimize hazards and the consequences of an unintended action. On the job: a shower valve that limits maximum temperature (see related: Anti-Scald Protection for an Older or Disabled User); ground-fault protection where water and power meet; a shower floor that slopes to its drain so a missed curtain does not flood the hall; rounded counter corners on a peninsula people walk past.
6. Low physical effort: it does not take strength. Neutral body position, reasonable force, little repetition. On the job: lever door handles and rocker switches rather than knobs and toggles (see related: Lever Handles and Controls a Hand Can Work); a single-lever faucet; an opener on a heavy garage door; a dishwasher drawer instead of a bend to the floor.
7. Size and space for approach and use: room for the body that shows up. Space to approach, reach and operate, whatever the user's size, posture or mobility. On the job: clear floor space in front of the panel, the water heater controls and the main shutoff; outlets and switches inside a reach range a seated person can use (see related: Reach Ranges and Control Heights); a doorway with enough clear width for a walker (see related: How to Measure Clear Width and Gain It Without Widening).
Where the principles pull against each other
The principles are not a checklist because they conflict, and the decision is in the conflict.
- Tolerance for error against low physical effort. A door closer stops a door slamming on fingers and makes the door harder to open. In a house, the usual answer is no closer on interior doors, and a soft-close hinge where a slam is the risk.
- Flexibility against simplicity. A thermostat with schedules, zones and modes is flexible; to a user with early memory changes it is unusable. Offer the simple control as the default and the flexible one as the option, not the other way round.
- Equitable use against cost. A zero-step entry is the equitable answer and can mean regrading a front walk. If the site will not allow it this year, put the blocking, the wider door and the level landing in now so the entry can be made step-free later without demolition.
When two principles conflict, the person who lives there settles it, which is why universal design on a known user's job becomes an assessment. See related: The Accessibility Walkthrough With the Person Who Lives There.
Worked example: a hall bath refresh for a couple in their fifties
A plumbing-and-remodel shop is gutting a hall bath for a couple in their fifties with no disability and no plans to move. The quote is for 32 crew-hours of labor: new tub-shower, vanity, toilet, lighting, tile. Nobody asked for accessibility.
The project lead runs the seven principles across the open walls and keeps the choices that cost little now and a lot later.
| Choice | Principle | Added labor | What it costs to do later |
|---|---|---|---|
| Plywood backing across the tub walls and beside the toilet | 5, 7 | 1.0 hr | Opening finished tile |
| Handheld shower on a slide bar, valve offset toward the room | 2, 7 | 0.25 hr | Moving a valve through tile |
| Offset hinges on the bath door | 7 | 0.5 hr | The same 0.5 hr, so it is optional |
| Switch moved from behind the door swing to the latch side | 3, 7 | 1.0 hr | Opening finished drywall |
| Lever faucet and lever door handle | 6 | 0 hr | A later swap, no wall work |
| Quarter-turn stops under the sink and toilet | 3, 6 | 0 hr (same part count) | A later swap, with the water off |
Added labor: 1.0 plus 0.25 plus 0.5 plus 1.0 is 2.75 hours on a 32-hour job, about 9 percent of labor (2.75 divided by 32). The materials add a sheet of plywood and a slide bar.
The reasoning behind each call. The backing and the switch move are the two items that are cheap only today, because both live inside a wall that will be tiled or finished this week. They stay in the quote as line items, not buried, so the couple can see what they are buying. The offset hinges cost the same now as later, so the project lead offers them and lets the couple decide. The lever hardware and the quarter-turn stops cost nothing extra; they are simply the default parts this shop now stocks.
What changes the answer. If the couple were selling in two years, the backing still earns its place (a buyer may need it) and the switch move might not. If one of them already used a cane, the job stops being universal design and becomes an accessibility job with a walkthrough, and the dimensions come from that person rather than from a reference. If the wall were not being opened at all (a tub swap through the existing tile), the backing would cost a tile demolition and comes off the list.
The failure mode. The common failure is not refusing universal design. It is doing all of it as a premium package nobody asked for, so the couple declines the package and with it the one hour of plywood that would have saved a tile demolition later. Sell the cheap-now items separately from the nice-to-have ones.
How to verify it on any job
Before the walls close, stand in each room and ask three questions: could someone sitting down use every control in this room, could someone with one good hand use them, and is there anything in this wall that a future grab bar, handrail or control would need? If the answer to the third is yes and the wall is open, put it in or tell the customer you did not, in writing. A note on the job record that says "blocking installed behind tub back wall, 32 to 38 in, photo attached" is worth more to the next contractor than any amount of memory.
References
- Center for Universal Design, North Carolina State University, The Principles of Universal Design, version 2.0 (1997)
- 2010 ADA Standards for Accessible Design, used as a dimensional reference for reach and clear space in a private home
- See related: What the ADA Does and Does Not Cover in a Private Home; Grab Bar Backing and Load: The Structural Rule; Reach Ranges and Control Heights; Lever Handles and Controls a Hand Can Work